As a conventional power generating structure using a piezoelectric element, for example, there are known a structure that applies an external force directly to a piezoelectric element, thereby deforming the piezoelectric element to obtain an electromotive force (see, for example, Patent Document 1), and a structure that applies a force such as a wind force indirectly to a piezoelectric element, thereby deforming the piezoelectric element to obtain an electromotive force (see, for example, Patent Document 2).
Such a conventional piezoelectric element is formed in a flat plate shape and one end thereof is fixed on an installation surface. The piezoelectric element can freely vibrate around the fixed end.    Patent Document 1: Japanese Patent Application Laid-open No. H7-49418    Patent Document 2: Japanese Patent Application Laid-open No. H11-303726